In the context of the present application, the term “paper” is used when reference is made to any product produced on a plant fiber base such as a web of paper or board.
Generally, webs of paper and board are coated in order to enhance their printability properties. Among other things, the purpose of the coating is to improve the smoothness and whiteness of the base web and, particularly with thin base webs, to increase the opacity of the web material. Conventionally, the coating is applied to the base web surface as an aqueous suspension. There may be applied a plurality of coat layers and the application of the coat layers can be accomplished using a number of different methods. Since all the conventional methods apply the coating as an aqueous suspension, the drying of the coat forms a massive step in the coating process. Drying of the coat is an energy-intensive process and the drying of a fast moving web needs a long dryer section in order to direct a sufficient amount of drying energy to the web. Also the routing of the web to be processed is difficult, because the web cannot be guided by any members contacting it from its wet side until the coating has become adequately dry.